Method of purifying commercial anthraquinone.



titan stra ns a;

I HAIR-RY F. LEWIS, F URBANA, ILLINOIS,

CALIFOPJNZA.

AND HARRY D. GIBBS, OF SAN FEADFGKSCQ,

METHOD OF PURIFYIN'G GOIdMEECKAL ANTHRAQUIHQNE.

Ho Drawing.

Specification of Letters Patent.

(FILED UNDER THE ACT OF MARCH 3, 1883, 22 STAT. I, 325.) To all whom it may concern:

Be it known-that we, HARRY F. Laws and HARRY D. GIBBS, citizens of the United States of America, and employees of the Department of Agriculture of the said United States, residing in the city of Urbana, county of Champai n, State of Illinois; and in the city of San Francisco, California, respectively, (whose post-ofice address is Washington, D. C.,) have invented a new and useful Method of Purifying Commercial Anthraquinone.

This appllcation is made under the act of March 3, 1883, chapter 143 (22 Stat, 625), and the invention herein described and claimed may be used by the Government of the United States or any of its ofioers or employees in the prosecution of work for the Government, or any person in the United States, without payment to us of any royalt thereon.

r invention relates to a process for the purification of anthraquinone.

It is well known that anthraquinone is ordinarily purified commercially by sublimation, in sublimers of various types. In this process there is a loss of an appreciable amount of an-thraquinone. The object of our invention is to provide a method for the purification of anthraquinone which will be free from the objectionable features of the sublimation method for the purification of anthraquinone.

@ur invention consists in the reduction of the insoluble anthraquinone to a soluble reduction compound, oxanthranol, by means of finely powdered iron in a solution of sodium or potassium hydroxid of certain concentrations and the ltration of this soluble compound; this may be easily reoxidized to anthraquinone by the action of air. In this way the anthracene and most of the other lmpurities commonly found in commercial 20% sodium hydroxid solution are added and the whole heated to 100 centigrade for 15 minutes. The contents of the vessel are -filtered rapidly through a filter press and the residue treated with a fresh alkaline solution and heated in a similar manner. llhis is filtered rapidly in the filter press and the Patented Feb. 41, 191%.. Application filed January as, 1913. Serial No. 213,979.

operation repeated a third time to insure the complete recovery of the anthraquinone. The combined filtrates are cooled and a stream of air assed through. This causes a reoxidation o. the oxanthranolto anthraquinone of a high degree of purity. This is filtered and dried. Having thus described our invention, we claim 1. A process for the purification of commercial anthraquinone which process con-' sists in subjecting anthraquinone in the solid staltiettov the action of finely divided iron and a o a and subsequent reoxidation of the reduced anthraquinone, by which means the anthraquinone is recovered in a very pure condition.

2. process for the purification of commercial anthraquinone .which process conline solution, and the filtration sists in subjecting anthraquinone in the solid state to the actlon of two partsof finely divided iron and thirty to slxty parts of a hot solution of sodium hydroxid containing from 10 'er cent. to 20 per cent. of sodium hydroxi and the filtration and subsequent reom'dation of the rwuced compound, by which means the anthraquinone is recovered in a very pure condition.

3. A process for thecommercial separation of anthraquinone from small or large amounts of anthracene by treating the commercial anthraquinone in a solid state to the action of finely divided iron and a hot alkaline solution, and the filtration and subsequent reoxidation of the reduced compound, by means of which the anthraquinone is reanthraquinonc, being soluble in the alkaline. covered in a very ure condition.

solution, are removed.

To illustrate the practical o eration of our In testimony w ereof, we afix our signatures in the presence of two subscribing recess we shall describe in etail the prewitnesses. erred plrocedure. One part of the common HARRY F. LEWIS. cial ant raquinone and two parts of fine iron RRY D- GIBBS- powder are mixed together in a suitable ves- Witnesses: V sel and are wet down with a liquid such as Einmnm,

50% alcohol. Thirty to fifty parts of hot 

